HANOVER – The state fire marshal’s office is investigating the cause of a three-alarm fire that destroyed a 21/2-story barn at 1011 Broadway on Saturday.

Two firefighters were evaluated for possible heat exhaustion while working to put out the fire. One was taken to South Shore Hospital, where he was treated and released.

State Forest Fire Warden Joshua Nigro, who was driving in the area, discovered the fire after smelling smoke. He alerted the homeowner, Floyd Williams, who called 911, according to a statement from the Hanover Fire Department.

Firefighters arrived at the scene shortly after 8:15 a.m. and found flames and smoke coming from the barn and threatening to spread to a house 20 feet away, the statement said.

The barn and its contents were destroyed. Chickens kept in the basement of the barn were led to safety by a neighbor.

Firefighters from Hanson, Pembroke, Rockland, Norwell and Marshfield assisted Hanover firefighters the scene. Station coverage was provided by Whitman and Abington.